Process of reacting sulphur trioxide



Dec. 10, 1968 1 F, LYNCH ET AL PROCESS OF REACTING SULPHUR TRIOXIDE 6Shee'bS-Sheet l Filed Sept. 18, 1964 dass Dec. 10, 1968 j- F, LYNCH ETALPROCESS 0F REACTING SULPHUR TRIOXIDE Filed sept. 18, 1964 6 Sheets-Sheet2 fil: ffii l.'

Dec. 10, 1968 J.F.x YN cH ETAL PROCESS OF REACTING SULPHUR TRIOXIDE 6Sheets-Sheetl 3 Filed sept. 18, 1964 Dec. 10, 1968 J. F, LYNCH ETALPROCESS oF REACTING sULPHUR TRIOXIDE 6 Sheets-Sheet 4,

Filed Sept. 18. 1964 Oom oom

Dec. l0, 1968 F, LYNCH ETAL 3,415,874

PRocEss oF REACTING suLPHun TRIoxIDE 6 Sheets-Shes?l 5 Filed sept. 18,1964 .mimi 3.52.5

.LndHSnOHI-LL :i0 ONDOdWOO 338i Dec.`10, 1968 J. F. LYNCH ETAL PROCESSOF REACTING SULPHUR TRIOXIDE 6 Sheets-Sheet 6 Filed Sept. 18, 1964 Nw ommn wn .vn Nm .LndHSnOBH-L :IO ONnOdWOO 338A United States Patent O 3415,874 PROCESS F REACTING SULPHUR TRIOXIDE John F. Lynch, Chester, andAlfred T. Wysocki, Chadds Ford, Pa., assignors to Marco DevelopmentCompany. Inc., Wilmington, Del., a corporation of Delaware Filed Sept.18, 1964, Ser. No. 397,509 3 Claims. (Cl. 260-505) ABSTRACT OF THEDISCLOSURE The present invention relates to a process of reactingsulphur trioxide in liquid form with an organic compound in liquid formusing a continuous reactor which has mixing impellers acting adjacent toheat transfer sur faces. The organic compound passes continuouslythrough the reactor in contact with at least four and preferably -atleast nine sets of impellers and heat transfer surfaces. In order toprevent backring, liquid sulphur trioxide is projected into the organiccompound at at least four impellers at a speed of at least 0.35 feet persecond and at a point not in excess of 0.5 inch from a heat transfersurface. Within a time of not less than 0.5 second from introduction ofthe liquid sulphur trioxide the mixture of organic compound `and liquidsulphur trioxide is subjected to liquid shear against a heat transfersurface. In a preferred embodiment the amount of sulphur trioxideprojected at the later impellers is increased with respect to thatprojected at the earlier impellers at geometrical progression.

DESCRIPTION OF INVENTION The present invention relates to reactingsulphur trioxide with an organic compound in liquid form, for example inorder to form sulphonates, sulfates or sulphamates.

A purpose of the invention is to react sulphur and oxygen with organiccompounds at lower cost -with a minimum of side reactions, charring anddegradation.

A further purpose is to obtain -a higher yield in reacting a compoundsuch as sulphur trioxide with an organic compound.

A further purpose is to make it possible to obtain an anhydroussulphonation, sulphation or sulphamation, thus avoiding the necessity toeliminate water from the reaction product which would be brought in inexcess with the reactants, or to ship water in the reaction productwhere it may not be desired.

A further purpose is to .avoid the necessity to use great excess ofsulphur trioxide or the like. l

A further purpose is to react sulphur trioxide with an organic compoundin liquid form, using a continuous reactor which has mixing impellersacting adjacent to heat transfer surfaces, by progressing the organiccompound in liquid form continuously. through the reactor in contactwith at least four sets of said impellers and heat transfer surfaces,projecting into the organic compound at each of the impellers at a speedgreat enough to avoid flashback of the reaction, liquid sulphur trioxideat a point not in excess of 0.5 inch from `a heat transfer surface, sothat cooling will be immediately available, and within a time of lessthan 0.5 second from introduction subjecting the mixture of organiccompound and sulphur trioxide to liquid shear against a heat transfersurface and thereby intimately mixing the organic compound and sulphurtrioxide and extracting heat of reaction therefrom.

A further purpose is to maintain the heat transfer surfaces adjacent theearlier impellers at a lower temperature than those adjacent the laterimpellers in the sequence of progression of the organic compound.

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A further purpose is to provide at least nine sets of impellers and heattransfer surfaces and to introduce liquid sulphur trioxide against eachof these impellers in a separate increment.

A further purpose is to project a greater .amount of sulphur trioxide atthe later impellers than that projected at the earlier impellers,desirably increasing the feed in geometrical progression.

A further purpose is to blow in -a gas containing oxygen into theorganic compound in the reactor, the gas desirably being air in aquantity of 0.013 to 0.109 cubic feet at standard conditions per poundof throughput of organic compound.

A further purpose is to modify the reaction where desired by introducinginto the organic compound in the reactor from 0.1 to 3% by weight ofWater calculated on the throughput.

Further purposes appear in the specification and in the claims.

The drawings include `apparatus useful for carrying out the process ofthe invention and curves illustrating results obtained by the invention.

FIGURE 1 is a ow diagram showing a typical embodiment of the process.

FIGURE 2 is a diagrammatic axial section of a series of impellers andheat transfer surfaces in a reactor which may be used in the invention.

FIGURE 3 is a transverse section through an impellcr chamber on the line3 3 of FIGURE 2.

FIGURE 4 is an exploded perspective of a heat transfer plate employed inthe reactor.

FIGURE 5 is a graph plotting free compound against percentage of excessof sulphur trioxide over the stoichiometric quantity.

FIGURE 6 is a graph plotting free compound against throughput totalweight in grams per minute.

FIGURE 7 is a graph plotting free compound in percentage of the totalthroughput against cubic feet of air per hour at standard conditionsinjected.

FIGURE 8 is a graph plotting free compound in percentage of throughoutagainst maximum temperature reached `within the machine in degreescentigrade.

A typical apparatus for carrying out the process of the presentinvention is shown in John Marco U.S. Patent No. 2,944,877, granted July12, 1960, for Chemical Apparatus for `Continuous Reactions, HeatExchanging, iMixing, Cooking and Other Chemical Processes.

Numerous processes have been developed in the prior art Ifor producingreactions of the character of sulphonation where the product wouldnormall be RSO3H, sulphation where the product would normall be ROSO3Hand sulphamation 'Where the product would normally be RZNSOSH.

The present invention concerns processes for this purpose which overcomecertain of the 4difficulties previously encountered in the prior art.

One diculty in the prior art has been that the product has tended to ibedark in color due to charting. One advantage of the present invention isthat light colored reaction products Iwith sulphur trioxide can beobtained at low cost.

Another diiculty in the prior art is that side reactions have tended toreduce the yield of the desired product. The present invention cuts downon the incidence of side reaction, which may express themselves bydegradation of the product produced.

Efforts have been made in the prior art to produce sulphonation,sulphation and sulphamation reactions by vaporizing SO'?l and thencausing the reaction to occur with the vapor phase S03. `This involvesvery complicated and relatively expensive equipment which is avoided bythe present invention, in which liquid phase S03 is caused to react,eliminating the need for creating and handling S03 vapor.

In some of the prior art practices where sulphuric acid in the form ofoleum or the like has been employed, needless and undesired quantitiesof water have been present which are costly to eliminate and which addto the bulk of the finished product. By the present invention thesulphonation, sulphation or sulphamation can be carried out in ananhydrous system where desired.

Also in some of the prior art practices a great excess of thesulphonating agent or the like has been employed. 'In the presentinvention it is no longer necessary to use such a large excess.

Some of the prior art practices have produced objectionable wastedisposal problems, either by creating sulphur contents in gases whichare difficult to eliminate, or by requiring `disposal of objectionableliquids. This is avoided by the present invention.

The liquid S03 which is used in the present invention can be obtainedfrom any suitable source, for example a sulphur burner or catalytic S03plant, and will normally be substantially pure S03, with an S03 contentolf better than 99% by weight and in most cases better than 99.5% byweight.

The liquid S03 is supplied on a continuous basis under proper control ofproportions to an organic compound in liquid `form with which thereaction is to take place. The organic compound will either be a liquidor be capable of being reduced to a liquid as by the presence of asolvent.

The excess of S03 over the stoichiometric requirements in most caseswill be of the order of 20 to 40% as later explained, but it will beevident that, depending on the dif'liculty of producing reaction, theexcess of S03 above the theoretical `quantity can be increased orreduced as desired.

In accordance with the present invention, the reaction is carried out ina continuous reactor which has a series of reaction chambers, each ofwhich is provided with a mixing impeller acting adjacent to heattransfer surfaces from which heat transfer can be accomplished by a heattransfer medium as later described. Each of the impellers is provided,yas also explained more in detail later, with an inlet jet or orificeopening by which the liquid S03 can be introduced.

The organic compound in liquid |form is thus progressed through thereactor chambers and successively comes in contact with one impeller andits heat transfer surfaces and then another impeller and its heattransfer surfaces, passing through at least four sets of impellers andheat transfer surfaces in the process of the invention. This permitsincremental addition of S03 in a manner as later explained whichminimizes damage or deterioration of the organic compound and reducesthe side reactions.

One of the important laspects of the present invention is the avoidanceof backring of the reaction at the S03 inlet jets, which has previouslybeen a serious obstacle in the way of sulphonation with S03 directly.

It is important in the present invention to prevent backfiring of thereaction by introducing the S03 at too slow a speed. Our experimentsindicate that the minimum speed for introducing the S03 withoutbackfirin-g is 0.35 f feet per second and for best results the speedshould exceed 0.7 feet per second. We have used in some cases withsuccess speeds as high as 8 or 10 feet per second. The size of theorifice is not critical, although in many cases we have used an orificesize of about l0.015 inch diameter, with a throughput of about two gramsper minute in the first orifice or about 65 grams per minute in fourorifices. It should be kept in mind that the pressure on the S03 mustovercome the pumping pressure on the compound being reacted and also thecentrifugal pressure on the compound.

When the S03 encounters the organic compound, it is important that theS03 contact the organic compound `for the lfirst time in an environmentfavorable for immediate mixing of the Sf03 and the compound andimmediate removal of heat produced by the reaction. At the point wherethe S03 contacts the organic compound, there should be a heat transfersurface within 0.5 inch so that long heat transfer through a body ofliquid is not required. Furthermore, the reaction proceeds so rapidlythat it is important that within a time of less than 0.5 second fromintroduction, the mixture of organic compound and sulphur trioxide mustbe subjected to liquid shear `against .a heat transfer surface oragainst the monomolecular film of liquid deposited thereon, so thatintimate mixing occurs between the components and heat can be extractedthrough the heat transfer surface. 0'ne of the features of the shear isthat the moving impeller surface shears the liquid against a heattransfer surface with a relatively close clearance of not more than.0125 inch and preferably not more than .003 inch. These are cylinderimpeller clearances. The -conditions favorable to -heat transfer becauseof the turbulence caused by the impeller and the close mechanicalclearance wiping the product film on the heat transfer plate.

Th-e organic compound is most susceptible to side reactions and tocharriug when the sulphur trioxide is first brought in contact with it,and therefore we believe it is important in many cases to maintain alower temperature at the first increment of sulphur trioxide additionthan the the temperature which is maintained at the later increments.This can be accomplished by maintaining a lower temperature on the heattransfer medium at the first increment or more rapidly fiowing the heattransfer medium at the first increment or a combination thereof. Thus,in a reaction between S03 and tridecylbenzene we find that usually goodresults are obtained if a ternperature of 20 to 30 degrees centigrade ismaintained at the first point of sulphur trioxide addition, atemperature 45 to 50 degrees centigrade is maintained at the next fourpoints of sulphur trioxide addition, and a temperature of 80 to 90degrees centigrade is maintained at the next four points of sulphurtrioxide addition used in the particular process.

In any case, we find that it is important to add the sulphur trioxide inat least four steps at at least four different impellers adjacentcorresponding heat transfer surfaces, although in the preferredembodiment We ernploy nine or ten such different incremental additionseach at a different impeller and adjoining a different heat transfersystem. Our experiments indicate that addition in several increments asabove described reduces the quantity of unreacted organic compoundpresent and reduces side reactions and charring of the organic compound.

Very superior results are obtained by adding a relatively small amountof sulphur trioxide in the first increment and increasing the quantitiesadded at the subsequent increments. For best results we find that theincrease should follow a geometrical progression. Thus, if the quantityof S03 introduced in the first orifice is measured by a factor of 2,that at the succeeding orifices will be measured by factors of 4, 8, 16,32, 64, etc. Good results from these progressively increasingincremental additions are obtained even without precisely following thegeometrical progression, and this general principle can be adhered towith a tolerance of i50% the quantity which the geometrical progressionwould require at a particular orifice, and still benefit is obtained.

In actual experiments adding the S03 incrementally in six steps, andwith progressive increase in successive additions, we have found thatthe quantity of unreacted organic compound can be cut to 5% in oneexample and 2% in another example, as compared with very much highervalues (30% and more) obtained from single additions of sulphurtrioxide. At the same time the color was lighter and anhydride formationwas reduced.

Optionally but very desirably, a gas containing oxygen is blown into theliquid organic compound at or adjacent the point where the first S03increment is added, preferably right after the addition of the rstincrement. The presence of the gas containing oxygen favors morecomplete reaction with the sulphur trioxide. Thus, in a particular casewhere without the presence of air the reaction was only 90% complete, inthe presence of air the yield was 98%.

Caution should be exercised in respect to this gas. Ox\ygen itself ifused in 100% concentration presents danger of detonation which mightdestroy the apparatus, but oxygen can be used in admixture with inertgases such as argon or carbon dioxide which reduce the danger ofdetonation.

For most purposes air is quite satisfactory. We iind that a feed of airof between 0.013 and 0.109 cubic feet of air at standard conditions andpreferably about 0.041 cubic feet of air at standard conditions perpound of reactant is satisfactory. This quantity was effective with 40%excess S03 above the stoichiometric requirement. The addition of the airreduced the quantity of unreacted organic compound (alkane 60) from 14%to 8% by weight although the color of the reaction product was slightlydarker.

In some reactions it is desirable to eliminate the presenceof waterentirely and employ an anhydrous reaction system. Sulphur trioxide,however, has a tendency to form anhydrides in which sulphur trioxidereacts with itself in producing rings or a chain, thus increasing thesulphur trioxide used in the reaction. This can be inhibited byintroducing Water at or adjacent to the point where the sulphur trioxideis rst introduced. Ihe addition of the water not only prevents theformation of anhydride, but tends to moderate the reaction and produce asomewhat lighter oil, without introducing the great quantities of wateror causing other disadvantages which would be present in using oleum. Wefind that good results can be obtained using water in proportions of 0.1to 3% by weight of the total quantity of throughput, preferably 2 to 3%by weight. This exerts a considerable moderating effect on the reaction.Hence, water can of course be introduced in several stages, for example,increments can be introduced at each point at which the S03 isintroduced if desired.

The process of the invention can be applied for reaction with sulphurtrioxide of a wide variety of organic compounds. Alkanes can be reacted,including saturated and unsaturated aliphatic hydrocarbons, withstraight or branched carbon chain, and without regard to chain lengthproviding they can be reduced to a liquid. The invention is widelyapplicable particularly to petroleum fractions. An alkane to which theinvention is widely applicable is alkane 60 mentioned below.

The invention is also applicable to producing the reaction withcarboxylic acids. Suitable alpihatic acids are acetic, propionic,butyric, oleic, linolenic and linoleic, and succinic and succinicanhydride. A suitable aromatic acid is benzoic acid.

The invention is widely applicable for producing reactions betweenaliphatic esters and sulphur trioxide, especially the fatty oils, suchas castor, soya bean, peanut, tallow, sperm, linseed, neats-foot and codliver.

The invention is also applicable to reacting sulphur trioxide withalcohols, such as ethylene glycol, glycerol, lauryl alcohol and dodecylalcoho.

The invention is applicable also to reactions with ketones, such asmethyl ethyl ketone and methyl isobutyl ketone.

The invention can be applied to reactions with amino compounds such asaniline, toluidine, and xylidine. Aldehydes may rbe reacted with sulphurtrioxide according to the invention, suitable materials beingformaldehyde and acetaldehyde. The invention is also applicable toreactions between sulphur trioxide and nitriles, such as acetonitrile.

The invention can be employed in sulphonation, sulphation andsulphamation of a wide variety of aromatic compounds, which are eithercarbocyclic or heterocyclic. Suitable examples are the aromatichydrocarbons, such as benzene, naphthalene, toluene, xylene, styrene;the nitrohydrocarbons, such as nitrobenzene and nitrotoluenes; and thephenols such as phenol, cresol and naphthol.

The invention can also be applied to reaction between sulphur trioXideand alkyl compounds such as dodecyl benzene, alkylated naphthalene,3-phenyl propionic acid, 3-phenyl stearic acid and S-phenyl caprioicacid.

Heterocyclic compounds will react, such as pyridine, furan, thiophene,quinoline and carbazole.

Silicone oils will react with S03 according to the invention.

The process of the invention can be followed by neutralization, forexample with a base such as sodium, potassium or ammonium hydroxide inwater, or an organic base such as an amine, such as triethanolamine.

In FIGURE 1 I show a suitable apparatus according to the presentinvention. A reactor suitably in the form of two separate reactor units20 and 20', to be described, has a succession of heat transfer plates 21to 2111, to be described, interposed by impeller chambers 22 to 229 tobe described. A tank 23 contains an organic compound in liquid form tobe sulphonated, sulphated or sulphamated, and this is withdrawn throughpiping 24, a flowmeter 25 and a metering pump 26, pressure beingindicated at 27, and introduced at 28 at lthe inlet end of the reactor20.

Liquid sulphur trioxide is contained in a storage tank 30 provided witha vent 31 protected from moisture by a drying tube 32. Liquid S03 iswithdrawn through a valve 33 and piping 34 through a owmeter 35 intobranch pipes 36 and 36 supplying the reactors 20 and 20'. The feed isaccomplished by metering pumps 37 or 37 through valves 38 and 38' toindividual branches 40 to 408 each of which enters radially into one ofthe impeller chambers 22 to 229. Each of the branches has in it a valve41 to control ow and a flowmeter 42 to measure it. Each of the branchpipes 36 and 36 has an accumulator 43 beyond the pump 37 or 37 set offby valves 44 and 45. The accumulator maintains gas pressure in thesystem to eliminate pump pulsations.

Each of the` branches 36 and 36 is also connected by piping through avalve 46 to a container of con- Centrated sulphuric acid 47 to permittesting of flow.

As shown in FIGURES 2, 3 and 4, the reactor has a central shaft 48turning by a suitable motor in suitable bearings not shown and has keyedthereon a series of impellers 50, best seen in FIGURES 2 and 3, whichare in cylindrical chambers 51, the impellers having in the middle ofthe cylindrical chamber a disc 52 passing from the shaft to a distanceof about a maximum of 1/8 inch from the interior of the chamber wall andpreferably a maximum of 1/16 inch, and integral therewith and on eitherside of the disc 52 there are placed involute blades 53 of which fourare shown, which on one side of the disc 52 extend in the forwarddirection and on the other side extend in the trailing direction. Theimpeller may turn in either direction but best results have beenobtained with the impeller turning in the trailing direction on the sidewhich rst encounters the reaction mixture. The blades 53 extend close tothe interior of the circumferential wall of the chamber 51, theclearance at 54 being suitable a maximum of 1A; inch and preferably amaximum of 1;/15 inch.

Extending radially inwardly suitably at the middle of the length of theimpeller chamber is a nozzle 55 which is suitably of round uniformdiameter and in a device having a throughput of about 2 grams per minutein the first port will conveniently be of a diameter of about 0.015 inchas previously explained. This nozzle 65 tends to direct the jet ofliquid sulphur trioxide on the outer ends of the impeller blades 53 sothat the liquid composed of the mixture of organic compound and sulphurtrioxide immediately undergoes shear in the clearance space 54. At thisinstant and throughout its ow through each of the impeller chambers theliquid is always within half an inch of one of the heat transfersurfaces 56 of the next heat transfer plate on either side as shown inFIGURE 4. This heat transfer plate, here shown as 21, has an annularspace 57, closed at the interior by a hub 58, the hub 58 leavingadequate clearance 60, FIGURE 2, between its interior and the shaft 48,so that the reaction mixture can flow from one impeller to anotherbetween the shaft and the hub 58 in the space 60. The ends of the space57 are closed by face plates 61 which when welded inside and out to thechamber 21' and to the hub 58 form a closed space in which the heattransfer medium can circulate from an inlet connection t at 62 to anoutlet connection at 63.

Thus, the organic chemical is introduced at 28 as shown in FIGURE 2 andows outwardly through the blades of one impeller and in heat transferrelation with one heat transfer plate, undergoes shear at the outsidebetween the blades and the interior of the cylindrical impeller chamber,comes in contact with a radially inwardly directed jet of sulphurtrioxide, is carried over the outer edge of the divider disc 52 andundergoes shear between the outer edges of another set of blades 53 andthe circumferential interior of the impeller chamber and then in flowingradially inwardly is forced in the clearance space 66 along the face ofthe heat transfer surface 56 and in Contact with its monomolecularliquid layer while shear takes place between the side of the blade ofthe impeller and the heat transfer surface. Clearance at 66 is regulatedso that it is between 0.002 and 0.0125 inch so that very effectiveliquid shear and very effective turbulence are obtained for heattransfer purposes. Finally, the mixture of organic compound and sulphurtrioxide which has now begun to react passes into the space 60 betweenthe hub 58 and the shaft 48.

Thus, in considerably less than a half of a second the reaction mixtureis brought into contact and in liquid shear relation with the heattransfer surface 56. This is repeated at each step along the reactorsystem. The reaction mixture passes from reactor to reactor by piping66. The reactor is held together by bolts 59.

Referring to FIGURE 1, heat transfer medium, suitably water, from asource `67 at an adequately low temperature is pumped by a metering pump68 through piping 62 into each of the heat transfer plates 21 to 2111and then pumped out through piping 63 and valve 64 to a sump 65.

If it is desired to operate the system without introducing any oxygencontaining gas and without introducing any water, then it will beevident that the partially reacted mixture passes through pipe 66 toenter the second reactor unit Successive increments of S03 are added atimpellers 22 to 229, the quantity being increased in geometricalprogression at the later station in the preferred embodiment.

In many cases it is desired to accomplish neutralization in the system,using a suitable base such as sodium hydroxide in water, and for thispurpose the `last impeller chamber 229 has a radial inlet 67 whichreceives neutralizing agent from a suitable source controlled by ametering pump not shown, supplied through a valve 70 and a flowmeter 71.

The nal neutralized product leaves by a pipe 72 through a valve 73 to astorageI tank 74 provided with a vent 75. A pressure gauge is shown at76, and by valve 77 a sample can be obtained at 73.

In many cases it is desired to introduce air or other oxygen containinggas to promote completeness of reaction. This is suitably accomplishedin the tirst impeller chamber 22 by withdrawing air from an air supply80 under pressure and directing it at a controlled rate through aowrneter 81 to a radial inlet 82. It is often desirable to introduce airalso in the second impeller chamber through a flowmeter 81 and `a radialinlet 82.

In some cases also to moderate the reaction and prevent the Aformationof anhydride, and whether or not air is introduced, it is desired tointroduce water from a water supply 83 under suitable pressure throughvalve 84, a flowmeter 85 and into a radial inlet 86 in the firstimpeller chamber 22.

The quantities of air and water which may be suitable have beendiscusse-d above.

An extensive series of experiments was carried out using an alkylbenzene h-aving a saturated hydrocarbon side chain of 10 to 15 carbonatoms which except that it is a crude product may be considered to betridecylbenzene having a specification as follows:

Gravity, API 29.5 to 31.0 Viscosity at F. SU (ASTM D88) 44 to 50 Color,Saybolt (ASTM D156) (minimum) +19 Bromine number (maximum) 0.5

Aniline point (ASTM D611) F 46 to 56 FIGURES 5 to 8 plot the resultsobtained by sulphonating alkane 60 according to the present inventionunder various conditions therein set forth.

Similar results were obtained in sulphonating doceylbenzene.

FIGURE 5 plots free compound as a percent of throughput against percentof excess S03 over the stoichiometric requirement. The test was run onalkane 60 at a temperature of sulphonation of about 50 centigrade andwith a throughput of about 300 grams per minute. It illustrates thatwith an excess of 20% S03 the free compound oonstituted about 19% of thethroughput but with an excess of S03 of 55% the free compound which wentthrough without reaction was reduced to about 4% by weight of thethroughput.

FIGURE 6 plots free compound in percent of the throughput as `ordinateagainst throughput in grams per minute and shows that as the throughputincreases the unreacted `component increases in almost a straight linerelation. These tests were run using alkane 60 with 20% by weight excessS03 at a temperature of about 55 centigrade.

FIGURE 7 plots the free compound in percent of the throughput asordinate and air injected in cubic feet per hour as the abscissa, thetest being run on sulphonation of alkane 60 with S03 with a 20% byweight excess of S03 at an operating temperature of 75 centigrade andwith a throughput of 300 grams per minute. This indicates that withinthe range of the test the quantity of unreacted compound wassubstantially independent of the quantity of air injected.

FIGURE 8 plots as ordinate the free compound in percent of throughputand as abscissa the maximum temperature within the reactor in degreescentigrade, the experiments being run on .alkane 60 sulphonated with S03with a 20% by weight excess of S03 and a throughput of 195 grams perminute. This indicates that as the reaction temperature increases, thequantity of unreacted organic compound reduces.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. A process of reacting sulphur trioxide in liquid form with an alkylbenzene, which comprises progressing said alkyl benzene in liquid formcontinuously through at least four reaction zones in sequence,

projecting into said alkyl benzene in each 0f said reaction zones at aspeed of at least 0.35 feet per second a jet of lliquid sulphur trioxideas such,

cooling the mixture of alkyl benzene and sulphur trioxide in eachreaction zone at a point not more than 0.5 inch -from the point at whichthe liquid sulphur trioxide contacts the alkyl benzene,

within a time of less than 0.5 second from introduction 10 of thesulphur trioxide into the alkyl benzene in each reaction zone shearingthe liquid mixture of sulphur trioxide and alkyl benzene in a liquidfilm not in excess of 0.0125 inch thick,

and thereby mixing the alkyl benzene and liquid sulphur trioxide andextracting heat of reaction therefrom so as to avoid explosion andvobtain a reaction product which is light in color.

2. A process of claim 1, which comprises projecting into saidalkyl'benzene said liquid sulphur trioxide in at least nine reactionzones according to claim 1.

3. A process of claim 1, which comprises increasing the amount ofsulphur troxide projected in the later reaction zones to that projectedin the earlier reaction zones in geometrical progression.

References Cited UNITED STATES PATENTS 2,768,199 10/1956 Lurtz et al.

LEON ZITVER, Primary Examiner,

H. ROBERTS, Assistant Examiner'.

U.S. Cl. X.R.

